POSTNATAL-DEVELOPMENT OF D1-DOPAMINE RECEPTORS IN THE MEDIAL PREFRONTAL CORTEX, STRIATUM AND NUCLEUS-ACCUMBENS OF NORMAL AND NEONATAL 6-HYDROXYDOPAMINE TREATED RATS - A QUANTITATIVE AUTORADIOGRAPHIC ANALYSIS

The postnatal development of dopamine (DA) D1 receptors in the medial prefrontal cortex (mPFC), striatum (STR) and nucleus (NAC) of control and perinatally 6-hydroxydopamine (6-OHDA) lesioned rats was examined using quantitative autoradiography of 3H-SCH 23390 binding. D1 receptors are present at one week and increase only slightly to a stable level by 2 weeks in the STR and NAC. Their ontogeny is not altered by intracisternal injection of 6-OHDA 5 days after birth. A biphasic pattern of appearance of D 1 receptors was found in the mPFC. D1 receptors are present in the mPFC at 1 week, increase 3-fold by 2-3 weeks, and then decline at 4 and 6 weeks. 6-OHDA lesions do not significantly alter this pattern. At all postnatal ages, D1 receptor binding in the mPFC exhibits a laminar distribution with increased receptor density in deep cortical layers (V, VI) compared to more superficial cortical layers (I, II). Both superficial and deep layers of D1 receptors in the mPFC show similar biphasic postnatal developmental patterns. DA turnover rates are consistently about 10-fold higher in frontal pole compared to remainder of forebrain at all postnatal ages. Early 6-OHDA lesions increase DA turnover in forebrain, but lead to a persistent reduction in DA turnover in frontal pole by 2 weeks of age.